EEACTION OF PLANETS UPON SUN PUISEUX. l7l( 



be eliminated and the effect of P would become evident by comparing 

 the conditions on the two hemispheres. 



It was found thus that the spotted areas tend to increase opposite 

 to Mercury and Venus, Jupiter, upon which the greatest hope was 

 placed, gave no definite result. 



The work of the Kew obserA^ers has been rather severely criticized. 

 The interval used seems too short for assuring the proper compensa- 

 tions, and the gaps in the data are considerable. The choice of the 

 material selected has not always seemed justified. 



RESEARCHES OF SCHUSTER. 



In a recent memoir {Proc. Roy. Soc. 85A, p. 309, 1911) A. Schuster 

 considered it advisable again to take up this problem, using the 

 Greenwich photographs for the years 1874 to 1909. He considered 

 only the births of spots lasting over the interval between the plates 

 of two successive da5^s. He excluded, as more subject to error, those 

 births which, seen from the earth, appeared at less than 30° of lon- 

 gitude from the eastern border. There remained 4,271 spots to 

 consider. 



For each planet P, the sun was divided into 12 equivalent vertical 

 zones. The solar meridian passing through the planet P formed the 

 boundary between the zones 6 and 7 on the hemisphere toward the 

 planet and between 12 and 1 on the farther side. The number of 

 spots seen for the first time in each zone was counted and used to 

 form a plot having as abscissse the zone numbers. 



The results are rather irregular especially if — as Schuster did at 

 first — we consider separately the spots counted when the earth is 

 east or west of the central meridian. Of the three planets — Mercury, 

 Jupiter, or Venus — each one seems to produce a minimum of spots 

 where another may produce a maximum. If the above distinction 

 is not made, the results seem more concordant. For all there is a 

 minimum upon zone 3, that is when the planet is just rising, 

 and a maximum on zone 8, which has already passed the meridian. 

 This can be compared with the diurnal march of temperature on 

 the earth due to the influence of the sun's heat. But there are other 

 intermediate maxima and minima for which the three planets are 

 in no ways in accord. 



Schuster, however, considers that the similarity of march of the 

 three curves for divisions 3 and 8 is sufficiently characteristic for 

 rendering very probable the reality of a planetary influence. 



This march is very different from that which had been found for 

 the earth and much less definite. The effective activity of the earth 

 is therefore apparently of another nature and relatively stronger, 

 or it is only apparent and due to the situation of the observer. 



